Check out example codes for "c++ get length of array". It will help you in understanding the concepts better.

Code Example 1

#include <iostream>
using namespace std;

#define size(type) ((char *)(&type+1)-(char*)(&type))

int main(){
  int arr[5] = {1, 2, 3, 4, 5};
  cout << size(arr) / size(arr[0]) << endl; //returns 5
  //alternatively
  cout << sizeof(arr) / sizeof(int) << endl; //returns 5
}

Code Example 2

int size = sizeof(arr)/sizeof(arr[0])

Code Example 3

int arr[5];
int len = sizeof(arr) / sizeof(arr[0]);
// returns 5

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